Have been looking at Netgear, Belkin, Billion. The Belkin boasts of 1gb speeds. Not sure this is ever realised, or likely to be?

It's unlikely any of your playback equipment can manage gigabit but it's always useful to have, most NAS's can do it and you can get cheap gigabit cards for a PC if it doesn't already have it. Whether you actually get 1Gb/s isn't the point, it should be much quicker than 100Mb/s.